CVE-2020-17752 in MillionCoin
Summary
by MITRE • 06/25/2021
Integer overflow vulnerability in payable function of a smart contract implementation for an Ethereum token, as demonstrated by the smart contract implemented at address 0xB49E984A83d7A638E7F2889fc8328952BA951AbE, an implementation for MillionCoin (MON).
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Analysis
by VulDB Data Team • 07/02/2021
The integer overflow vulnerability identified in CVE-2020-17752 represents a critical flaw within the Ethereum smart contract ecosystem that directly impacts the security and integrity of digital asset transfers. This vulnerability specifically affects the payable function of a smart contract implementation for the MillionCoin (MON) token, as evidenced by the contract deployed at address 0xB49E984A83d7A638E7F2889fc8328952BA951AbE. The flaw manifests when the contract processes transactions involving token transfers, creating a scenario where mathematical operations exceed the maximum allowable integer values, leading to unexpected behavior and potential exploitation.
The technical nature of this vulnerability stems from improper input validation and arithmetic operation handling within the smart contract code. When the payable function processes token transfers, it fails to adequately check for integer overflow conditions before performing mathematical calculations. This allows attackers to manipulate transaction parameters in such a way that the result of arithmetic operations wraps around to an unexpectedly small value, effectively bypassing intended security checks and access controls. The vulnerability aligns with CWE-190, which specifically addresses integer overflow and underflow conditions in software implementations. This particular flaw demonstrates how seemingly benign contract functions can become attack vectors when proper boundary checking mechanisms are absent.
The operational impact of this vulnerability extends beyond simple financial loss, potentially enabling sophisticated attacks that can compromise the entire token ecosystem. An attacker exploiting this integer overflow could manipulate token balances, create unlimited supply of tokens, or redirect funds to unauthorized addresses. The consequences are particularly severe given that this vulnerability affects a token implementation that likely serves as a utility within a broader decentralized finance ecosystem. The attack surface is further expanded by the fact that such vulnerabilities often compound with other weaknesses in smart contract architectures, creating cascading security risks that can affect multiple contracts or protocols. This aligns with ATT&CK technique T1499.004, which describes the exploitation of vulnerabilities to manipulate financial systems and asset transfers.
Mitigation strategies for this vulnerability require immediate code review and patching of the affected smart contract implementation. Developers must implement comprehensive input validation mechanisms that check for potential overflow conditions before performing arithmetic operations, particularly in functions handling token transfers and value manipulations. The recommended approach involves utilizing overflow protection libraries and implementing explicit boundary checks that prevent integer wraparound behaviors. Additionally, formal verification techniques should be employed to systematically analyze contract code for similar vulnerabilities, ensuring that all mathematical operations within smart contracts properly handle edge cases. Regular security auditing and testing protocols should be established to identify and remediate such issues before they can be exploited in production environments, as this vulnerability demonstrates the critical importance of robust security practices in blockchain-based systems.